Constraint-Induced Movement (CIM) or "forced use" therapy may be one treatment to improve sensorimotor recovery after stroke. Upper extremity motor impairment after stroke is associated with increased mortality, decreased functional status, and higher likelihood of institutionalization CIM for motor recovery after stroke involves restraining the unaffected extremity in order to encourage active use of the hemiplegic upper extremity. A series of animal studies have shown that sensory or motor loss associated with motor system lesioning or unilateral deafferentation could be overcome by restraining the unaffected limb in order to induce the animal to use the affected limb. The Aim of this proposal is to gather the data necessary to design a definitive randomized, controlled trial of the very early application of constraint induced movement (CIM) therapy for ischemic stroke. We will conduct a singlecenter RCT of CIM during inpatient rehabilitation in order to: Study a larger (n=80) subject group to more accurately estimate the magnitude of efficacy Refine the intervention via a dose-escalation study, testing a "high-intensity" CIM study ann. Select optimal primary and secondary trial endpoints, and estimate power for pivotal multicenter trial. Determine safety in a larger group, particularly regarding activity-dependent lesion enlargement, with MR imaging Use kinematic analysis to determine the biological significance of imaging findings and to gain a better understanding of the clinical measures of upper extremity function.